The major psychiatric disorders are both common and familial. Affected individuals tend to have immediate relatives who suffer the same type of disorder and many generations of a kindred may contain affected individuals. For some illnesses such as schizophrenia and the major affective disorders, there is evidence that both genes and environment are important. Our Center includes theoretical and clinical approaches to understanding this important phenomenon. New methods are being developed for the measurement of early environmental factors and the way in which genetic and environmental factors interact to produce disorders is also being studied. Projects which improve methods for the assessment of early family environment; a study of the genetics of pre-senile and senile Alzheimer's dementia; and several theoretical projects whose goal is the development of new statistical approaches to gene-environment interactions are included. In addition there is a core of essential personnel who offer guidance to other Center members. New Projects are being developed and will be submitted for approval. An important Center activity is the participation of many professionals from diverse disciplines in an educational and training program. The result has been an exciting, intellectual environment and the creation of new approaches to an age old problem.